---
id: CVE-2026-72423
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Guard conntrack opts error writes

  The conntrack lookup and allocation kfuncs take an opts pointer
  together with an opts__sz argument
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Guard conntrack opts error writes

  The conntrack lookup and allocation kfuncs take an opts pointer
  together with an opts__sz argument. The verifier checks only the…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= b4c2b9593a1c4c3a718370e34af28e817fd5e5c6 <
    453f4f1e90de55b6bc297936031b68bef93f2e28
  - >-
    Linux >= b4c2b9593a1c4c3a718370e34af28e817fd5e5c6 <
    dd74c80203842a21b2ebb9f70d1260d9aa20fa05
  - >-
    Linux >= b4c2b9593a1c4c3a718370e34af28e817fd5e5c6 <
    6f6183a39533d727deaa5061cadae6dd9e6744d0
  - Linux 5.18
published: '2026-08-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T11:17:43.567'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-72423'
references:
  - url: 'https://git.kernel.org/stable/c/453f4f1e90de55b6bc297936031b68bef93f2e28'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6f6183a39533d727deaa5061cadae6dd9e6744d0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/dd74c80203842a21b2ebb9f70d1260d9aa20fa05'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72423.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-72423'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2516305'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-72423'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-72423'
  - url: >-
      https://lore.kernel.org/linux-cve-announce/2026081526-CVE-2026-72423-9fac@gregkh/T
  - url: 'https://git.kernel.org/stable/c/669bc3b345712112d3f033a1953f5a10b15e7c65'
  - url: 'https://git.kernel.org/stable/c/63d95c6bbd6fc0e411404188306a1fea456300b0'
  - url: 'https://git.kernel.org/stable/c/6fd973def4d6cb89aaf7e9b6bc26cac977f6da13'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00165
epssPercentile: 0.05732
ingestedAt: '2026-10-15T11:00:41.685Z'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T18:49:41.501757Z'
cwe:
  - CWE-787
scores:
  nvd: 8.8
  vendor: 5.5
  cna: 8.8
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

bpf: Guard conntrack opts error writes

The conntrack lookup and allocation kfuncs take an opts pointer
together with an opts__sz argument. The verifier checks only the memory
range described by opts__sz, but the wrappers unconditionally write
opts->error whenever the internal lookup or allocation helper returns an
error.

For an invalid size smaller than the end of opts->error, that write can
land outside the verifier-checked range. Keep returning NULL for invalid
arguments, but only report the error through opts->error when the
supplied size includes the field.

This preserves error reporting for the supported 12-byte and 16-byte
layouts, and for other invalid sizes that still include opts->error.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 9 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72423.json)